protected function validate($data){
		$response = array();
		if ( 0 == $data['price'] ) {
			$response['error']       = 1;
			$response['error_field'] = 'mortgage_amount';
			$response['message']     = $this->calculator_settings['purchase_price_error'];
		} elseif ( 0 == $data['interest'] ) {
			$response['error']       = 1;
			$response['error_field'] = 'interest_rate';
			$response['message']     = $this->calculator_settings['interest_rate_error'];
		} elseif ( ! is_numeric( $data['down'] ) ) {
			$response['error']       = 1;
			$response['error_field'] = 'down_payment';
			$response['message']     = $this->calculator_settings['down_payment_error'];
		} elseif ( 0 == $data['term'] ) {
			$response['error']       = 1;
			$response['error_field'] = 'term';
			$response['message']     = $this->calculator_settings['term_error'];
		}

		if (isset($response['error']) && 1 === $response['error'] ) {
			header( 'content-type: application/json' );
			echo wp_json_encode( $response );
			wp_die();
		}
	}